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Unrelated, how bad is it to look without protection during totality? We got the approved eclipse glasses and diligently kept them on through the whole lead-up,

Unrelated, how bad is it to look without protection during totality? We got the approved eclipse glasses and diligently kept them on through the whole lead-up, then couldn't see shit once totality started, so we took them off and gazed at the loveliness and then hastily put them back on t moment the sun started to re-emerge. I get that it's not good to tell the public "don't look at an eclipse unprotected except for this precisely-timed period," because that would lead to a statistically significant increase in permanent eye damage, but what we did seems to have gone fine, at least when exposures are circa once a decade.

LegionMammal978 2y ago
The general advice (at least from everything I've seen) is that you can and should remove your eclipse glasses during totality; after all, the bright surface of the sun is totally blocked. I personally looked into the research on solar eye damage a few years ago (when the 2017 eclipse fervor had died down), and my impression is that all recorded cases result from focusing directly at the sun for at least several seconds straight; glancing very briefly at the sun, or seeing it in your peripheral vision, is only uncomfortable at worst. Eye damage is mainly associated with eclipses since they motivate many people to stare at the sun, rather than the partially-eclipsed sun being uniquely dangerous to look at. But when the time comes around, the messaging gets very black-and-white, as you said. (Not that it's a bad idea to avoid looking at the sun as much as possible!)
- schoen 2y ago
  I've also been interested in this in the past since I slightly damaged my eye by staring at a partial eclipse as an adolescent. (I can no longer perceive any damage, but it might have permanently reduced my retinal acuity in one spot.) > Eye damage is mainly associated with eclipses since they motivate many people to stare at the sun, rather than the partially-eclipsed sun being uniquely dangerous to look at. Most sources seem to agree with that, and that's basically my impression. But I do know of another theory, which is that damage is associated with something like J/m² absorbed energy, and so roughly with (W/m² × s) of exposure, but the blink or discomfort reflex is associated with something more like total W entering the eye. The way that the sun is obscured during a partial eclipse is not by dimming (which would reduce both the total power entering the eye and the total power absorbed by a given region of the retina by the same factor), but instead by making a portion of the solar disc invisible, while leaving other portions fully visible. Those portions are still causing a comparable absorption of energy per second on the parts of the retina where they are focused, but the partially-obscured sun, in addition to being much more interesting, might be less uncomfortable to stare at because of the total amount of light being lower. Sorry if that account was too wordy. A more concise way of putting it might be: Your desire to look away after a relatively short time is based on the total amount of light entering your eye (which is reduced during a partial eclipse), but the sun's ability to damage your eye is based more on the total amount of light focused on a given part of your retina (which is not reduced very much, since the parts of the sun you can still see are just about as bright as usual). I don't know whether that interpretation is right, but it's another wrinkle on the "you're more inclined to stare at the sun during an eclipse than you usually would be" issue: it might not be exclusively because it's more interesting, but also because the total light is less than usual, so your discomfort is less than usual, but your risk of injury per second is only very slightly decreased. Related to this, we don't have pain receptors directly on the retina itself, so the feeling of discomfort we get when looking at a bright light isn't directly indicating whether the retina is being damaged or not.
  - throwaway290 2y ago
    Don't our eyes adjust, so if it seems like the sun is obscured the pupils would dilate increasing potential damage?
    - schoen 2y ago
      That's also an issue for some scenarios, but if you're looking directly at the sun (even partly obscured), your pupils are probably already as small as possible!
  - catlikesshrimp 2y ago
    UV light is not visible, but it is high energy electromagnetic waves. Your brain doesn't process "excess light" because your eyes aren't sensing visible light. They are being exposed to damage by the rest of the light, nonetheless.
    - schoen 2y ago
      Yes, but I don't think there's more UV during an eclipse (even in proportion to visible light). Overall, there should be less UV than there would be from viewing the full sun. The issue you mention does come up if you have a filter that blocks visible light but not UV. Non-UV-blocking sunglasses, for example, could increase the risk of cataracts compared to not wearing sunglasses at all (mainly because of pupil dilation).
  - LegionMammal978 2y ago
    Thanks for elaborating! I remembered hearing something to that extent back in 2017, but after I couldn't find any primary sources on it online, I'd dismissed it as a rumor. Absolute duration would still be the primary factor, in any case. Luckily I've never had any eye problems myself, but not for lack of trying. Back in elementary school, I would occasionally stare at the outdoor sun for 30 seconds or longer, just to see what could possibly be so bad about it. Yet my eyes remain undamaged, at least as far as any optometrist has told me. Hence why I was skeptical about the supposed danger of eclipses. But perhaps the interval before damage can be much shorter, depending on age and other factors.
- noqc 2y ago
  Failing to look at totality during an eclipse because of too coarse public health guidelines (predicated on the fact that you're an idiot) is tragic.
noqc 2y ago
During totality, there is no danger to your eyes to looking directly at the corona. You can tell on account of how it isn't bright.

LegionMammal978 2y ago

The general advice (at least from everything I've seen) is that you can and should remove your eclipse glasses during totality; after all, the bright surface of the sun is totally blocked. I personally looked into the research on solar eye damage a few years ago (when the 2017 eclipse fervor had died down), and my impression is that all recorded cases result from focusing directly at the sun for at least several seconds straight; glancing very briefly at the sun, or seeing it in your peripheral vision, is only uncomfortable at worst. Eye damage is mainly associated with eclipses since they motivate many people to stare at the sun, rather than the partially-eclipsed sun being uniquely dangerous to look at. But when the time comes around, the messaging gets very black-and-white, as you said. (Not that it's a bad idea to avoid looking at the sun as much as possible!)

schoen 2y ago
I've also been interested in this in the past since I slightly damaged my eye by staring at a partial eclipse as an adolescent. (I can no longer perceive any damage, but it might have permanently reduced my retinal acuity in one spot.) > Eye damage is mainly associated with eclipses since they motivate many people to stare at the sun, rather than the partially-eclipsed sun being uniquely dangerous to look at. Most sources seem to agree with that, and that's basically my impression. But I do know of another theory, which is that damage is associated with something like J/m² absorbed energy, and so roughly with (W/m² × s) of exposure, but the blink or discomfort reflex is associated with something more like total W entering the eye. The way that the sun is obscured during a partial eclipse is not by dimming (which would reduce both the total power entering the eye and the total power absorbed by a given region of the retina by the same factor), but instead by making a portion of the solar disc invisible, while leaving other portions fully visible. Those portions are still causing a comparable absorption of energy per second on the parts of the retina where they are focused, but the partially-obscured sun, in addition to being much more interesting, might be less uncomfortable to stare at because of the total amount of light being lower. Sorry if that account was too wordy. A more concise way of putting it might be: Your desire to look away after a relatively short time is based on the total amount of light entering your eye (which is reduced during a partial eclipse), but the sun's ability to damage your eye is based more on the total amount of light focused on a given part of your retina (which is not reduced very much, since the parts of the sun you can still see are just about as bright as usual). I don't know whether that interpretation is right, but it's another wrinkle on the "you're more inclined to stare at the sun during an eclipse than you usually would be" issue: it might not be exclusively because it's more interesting, but also because the total light is less than usual, so your discomfort is less than usual, but your risk of injury per second is only very slightly decreased. Related to this, we don't have pain receptors directly on the retina itself, so the feeling of discomfort we get when looking at a bright light isn't directly indicating whether the retina is being damaged or not.
- throwaway290 2y ago
  Don't our eyes adjust, so if it seems like the sun is obscured the pupils would dilate increasing potential damage?
  - schoen 2y ago
    That's also an issue for some scenarios, but if you're looking directly at the sun (even partly obscured), your pupils are probably already as small as possible!
- catlikesshrimp 2y ago
  UV light is not visible, but it is high energy electromagnetic waves. Your brain doesn't process "excess light" because your eyes aren't sensing visible light. They are being exposed to damage by the rest of the light, nonetheless.
  - schoen 2y ago
    Yes, but I don't think there's more UV during an eclipse (even in proportion to visible light). Overall, there should be less UV than there would be from viewing the full sun. The issue you mention does come up if you have a filter that blocks visible light but not UV. Non-UV-blocking sunglasses, for example, could increase the risk of cataracts compared to not wearing sunglasses at all (mainly because of pupil dilation).
- LegionMammal978 2y ago
  Thanks for elaborating! I remembered hearing something to that extent back in 2017, but after I couldn't find any primary sources on it online, I'd dismissed it as a rumor. Absolute duration would still be the primary factor, in any case. Luckily I've never had any eye problems myself, but not for lack of trying. Back in elementary school, I would occasionally stare at the outdoor sun for 30 seconds or longer, just to see what could possibly be so bad about it. Yet my eyes remain undamaged, at least as far as any optometrist has told me. Hence why I was skeptical about the supposed danger of eclipses. But perhaps the interval before damage can be much shorter, depending on age and other factors.
noqc 2y ago
Failing to look at totality during an eclipse because of too coarse public health guidelines (predicated on the fact that you're an idiot) is tragic.

noqc 2y ago

During totality, there is no danger to your eyes to looking directly at the corona. You can tell on account of how it isn't bright.